One-time passcode (OTP) authentication tokens may be implemented in hardware and software. Hardware authentication tokens are typically implemented as small, hand-held devices that display a series of passcodes over time. A user equipped with such an authentication token reads the currently displayed passcode and enters it into a computer or other element of an authentication system as part of an authentication operation. This type of dynamic passcode arrangement offers a significant security improvement over authentication based on a static password. Software authentication tokens, or software authenticators, can be implemented in the form of software installed on a processing device such as a computer, mobile phone, tablet, etc.
Conventional authentication tokens include both time-synchronous and event-synchronous tokens.
In a typical time-synchronous token, the displayed passcodes are based on a secret value and the time of day. A verifier with access to the secret value and a time of day clock can verify that a given presented passcode is valid.
One particular example of a time-synchronous authentication token is the RSA SecurID® user authentication token, commercially available from RSA, The Security Division of EMC Corporation, of Bedford, Mass., U.S.A.
Event-synchronous tokens generate passcodes in response to a designated event, such as a user pressing a button on the token. Each time the button is pressed, a new passcode is generated based on a secret value and an event counter. A verifier with access to the secret value and the current event count can verify that a given presented passcode is valid.
Other known types of authentication tokens include hybrid time-synchronous and event-synchronous tokens.
Passcodes can be communicated directly from the authentication token to a computer or other element of an authentication system, instead of being displayed to the user. For example, a wired connection such as a universal serial bus (USB) interface may be used for this purpose. Wireless authentication tokens are also known. In authentication tokens of this type, the passcodes are wirelessly communicated to a computer or other element of an authentication system. These wired or wireless arrangements, also referred to herein as connected tokens, save the user the trouble of reading the passcode from the display and manually entering it into the computer.
Hardware and software authentication tokens and other types of OTP devices are typically programmed with a random seed or other type of key that is also stored in a token record file. The record file is loaded into an authentication server, such that the server can create matching passcodes for the authentication token based on the key and the current time or current event count.